Monitoring Java Safepoint Time in JDK16+

[Carter Kozak]

On 17/06/2021 3:15 pm, Alan Bateman wrote:
> On 17/06/2021 02:39, David Holmes wrote:
>> In what way does this no longer work? We have a test in
>> jdk/sun/management/HotspotRuntimeMBean/GetTotalSafepointTime.java that
>> uses this API and doesn't seem to need to do anything to allow access. ??
> That test is compiled/run with `--add-exports
> java.management/sun.management=ALL-UNNAMED`, just not immediately
> obvious because the TEST.properties with the config for jtreg is in the
> parent directory (it applies to tests in that directory and all
> sub-directories). Carter would have need the equivalent to compile with
> JDK 9+ and to run with JDK 16+.

Thanks for the clarification! The trouble is that I maintain a microservice framework/library which produces metrics, however I don't have access to provide java arguments in most cases. I'd prefer to avoid requiring additional manual action from my users when they upgrade to the next java LTS, especially given we don't want to get into the habit of opening additional modules after the fact. This is useful information as a break-glass measure, and something I can work with, but I'd like to work toward an end state in which there's an exposed public API to capture safepoint metrics. The JFR event stream may be that mechanism, although I'm not sure the overhead/tradeoffs make sense as a replacement given we're already aggregating safepoint time elsewhere in memory.

Thanks,
Carter

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